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 A164572 Numbers n such that n and n+4 are prime powers. 6
 1, 3, 4, 5, 7, 9, 13, 19, 23, 25, 27, 37, 43, 49, 67, 79, 97, 103, 109, 121, 127, 163, 169, 193, 223, 229, 239, 277, 289, 307, 313, 343, 349, 379, 397, 439, 457, 463, 487, 499, 613, 643, 673, 729, 739, 757, 769, 823, 853, 859, 877, 883, 907, 937, 967, 1009, 1087 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Numbers n such that n + (0, 4) is a prime power pair. A generalization of the cousin primes. The cousin primes are a subsequence. n + (0, 2m), m >= 1, being an admissible pattern for prime pairs, since (0, 2m) = (0, 0) (mod 2), has high density. n + (0, 2m-1), m >= 1, being a non-admissible pattern for prime pairs, since (0, 2m-1) = (0, 1) (mod 2), has low density [the only possible pairs are (2^a - 2m-1, 2^a) or (2^a, 2^a + 2m-1), a >= 0.] LINKS Daniel Forgues, Table of n, a(n) for n = 1..1256 PROG (PARI) is(n)=if(n==1, return(1)); isprimepower(n) && isprimepower(n+4) \\ Charles R Greathouse IV, Apr 24 2015 CROSSREFS Cf. A006549 Numbers n such that n and n+1 are prime powers. Cf. A023200, A000961. Cf. A120431 Numbers n such that n and n+2 are prime powers. Cf. A164571 Numbers n such that n and n+3 are prime powers. Cf. A164572 Numbers n such that n and n+4 are prime powers. Cf. A164573 Numbers n such that n and n+5 are prime powers. Cf. A164574 Numbers n such that n and n+6 are prime powers. Sequence in context: A226918 A227391 A209721 * A067530 A259796 A082922 Adjacent sequences:  A164569 A164570 A164571 * A164573 A164574 A164575 KEYWORD nonn AUTHOR Daniel Forgues, Aug 16 2009, Aug 17 2009 STATUS approved

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Last modified March 26 06:48 EDT 2019. Contains 321481 sequences. (Running on oeis4.)